The present invention relates to a hard disk drive used as an auxiliary memory device in a computer, and more particularly, to a magnetic latching apparatus for an actuator of the hard disk drive for maintaining the actuator of the hard disk drive in a parking zone while the actuator is not in operation.
Generally, the hard disk drive used as the auxiliary memory device in the computer includes a disk which is rotated at a high speed by a spindle motor, and an actuator which rotates in response to a voice coil motor about a pivot point for moving a magnetic head that writes data onto tracks of the disk and reads data recorded on tracks of the disk. The magnetic head is located on a leading end of a head gimbals, which moves along both sides of the disk, wherein the magnetic head is influenced by an airflow generated on a surface of the disk as the disk rotates at a high speed to maintain a minute air gap between the magnetic head and the disk.
When the hard disk drive stops or electrical power is turned off during the above-mentioned operation, the actuator is installed to move the magnetic head into a parking zone located on an inner or an outer portion in the tracks of the disk. Upon interruption of electrical power to the hard disk drive, the actuator is adjusted to move the magnetic heads into the parking zone on the disk by a residual inertia of a spindle motor. This is designed to prevent the data recorded on the disk from being damaged due to undesired contact of the magnetic head against the surface of the disk.
For stably fixing or latching a rear end of the actuator during the above operation, a device such as a solenoid, a separate voice coil motor or a magnetic latch has been employed. Among these, the magnetic latch is generally used. In this case, a metal plate easily attached to a magnet has to be installed to the rear end of the actuator, since the rear end of the actuator is made of an aluminum material, or has a structure to which a coil may be attached. Generally, in the case where the structure having a metal plate is used, the metal plate can be attached to the rear end of the actuator by using in adhesive material. When the adhesive material is used within the hard disk drive, there are disadvantages because gas generated during the time it takes the adhesive material to solidify mad dust generated due to a change of an element of the adhesive material over time deleteriously effect the reliability of the hard disk drive.
One conventional disk drive design incorporating an electric latching technique uses a solenoid or a separate voice coil motor, thus requiring an additional device for controlling these components. This results in another problem that the cost of product is accordingly raised due to an increased price of manufacturing the device. An example of this type of design, such as U.S. Pat. No. 5,189,576 entitled Rotary Inertial Latch For Disk Drive Actuator to James H. Morehouse, et al., uses a mechanical latch responsive to an inertial force of the actuator for moving a latch pin to engage a finger extending from the actuator in order to maintain the actuator in its proper position when the disk drive is not in operation. There are disadvantages in using this conventional latch because a complicated device using a damper or a spring to buffer impact generated upon the parking of the head is used; consequently the cost of the product is accordingly raised, and difficulties of assembly and repair are incurred.
In another example, John B. Blanks discloses in U.S. Pat. No. 5,231,556 a Self-Holding Latch Assembly using a magnetic latch assembly mounted on a magnet coil assembly that rotates about a pivot pin to confine a latch pin, extending from the side of an actuator by an arm, between a latch arm of the magnetic latch assembly and a travel stop, in order to lock the actuator in a parking zone.
A somewhat different approach, found in U.S. Pat. No. 5,224,000 entitled Crash Stop And Magnetic Latch For A Voice Coil Actuator by Shawn E. Casey, et al., uses a magnetic latch for holding an actuator in a home or park position. The magnetic latch is constructed with a pair of magnetic "L" shaped slidable poles disposed on opposite sides of a magnet, wherein the poles are of a greater length than the magnet so that a steel strike plate attached to the actuator contacts the poles to prevent the strike plate from hitting the magnet. The magnetic latch is slidably mounted in a recess of a bumper pad disposed within a frame of a bumper stop mounted on the lower casing of the housing, with the poles extending beyond a contact surface of the bumper pad. Another magnetic latch, U.S. Pat. No. 5,023,736 entitled Magnetic Latch For Disk Drive Actuator by Gary Kelsic, et al., has a magnetic latch having a pair of spaced apart parallel poles extending from a magnet for latching onto a latch plate extending from a disk drive actuator for maintaining the actuator in a crash stop, or parked position when desired. The magnetic latch is housed in a cavity formed in a molded plastic housing attached to the disk drive housing. Kai C. K. Sun, et al., in U.S. Pat. No. 5,003,422 entitled a Magnetic Locking Mechanism, shows a magnetic latch, having a resilient mechanism connected to a support structure for dampening the impact of the actuator as an actuator pin extending from the actuator strikes a swing plate of the resilient mechanism. Movement of the swing plate causes the top of the swing plate to move against the resistance of a spring in response to the bottom of the swing plate being struck by the actuator. A magnet attached to the bottom of the swing plate latches onto an actuator pin extending from the actuator when the actuator is placed in park.
While these designs provide a modicum of improvement in their own right, their tendency towards bulkiness hinders efforts to further miniaturize the volume occupied a disk drive.